5. you can't make speculation illegal. you'd have a tough time even defining it.

what you can do is cut down on LEVERAGE, by simply increasing the margins or capital requirements that already exist on futures and comparable derivatives. done properly, it would still let people help set the price properly, yet limit the influence of those without an immediate supply or demand need for the underlying asset.

for example, the initial margin for a nymex futures contract for 1,000 barrels of light sweet crude oil is a mere $6,885. so you can control about $100,000 worth of oil merely by putting up $6,885. if they were to double this, people would be able to control half as much oil for the same margin. this drives speculators away but the hedgers are stuck and have to play (though they may not like it much). this way, the market power shifts toward the people with genuine supply/demand needs.

the futures markets exist for a reason, which is that the market for people with genuine supply/demand needs simply works better when others are able to reasonably participate. the trick is to constantly set the margins in a range that doesn't let the speculators run rampant, not squeezes them out entirely.

i would opine that a 14:1 leverage ratio is permits too much leverage and that the margins should be raised a fair amount from here, at least doubled.